cannot sign in

I cannot sign in using all the three ways my Zoom offers.
a. Send a code to another device ---- never got the code to any of my other devices
b. Send a code to me gmail ---- got the email but every time I entered this code, Zoom tells me the code has expired even though it was within 10 min
c. SMS verification ---- Zoom shows verification code sending failed, and I never got the message

I created an open ticked but immediately got the email saying "Unfortunately, we are unable to respond to your open ticket at this time."

I have to hold a meeting 24 hours later and I am very worried.

Thanks in advance for any helps.